Mechanical rectifier



April 4, 1950 E. n n-:BOLD MECHANICAL RECTIFIER 3 Sheets-Sheet 1 Filed Feb.` 12, 1946 Armafure Move/"enf WIP U.. Uw.

11 Jima b3 ...Q .$58

API'il 4, 1950 E. Dls-:BOLD 2,502,932

MECHANICAL RECTIFIER Filed Feb. 12. 1946 3 Sheets-Sheet 2 April 4, 1950 E. DIL-:BOLD

MECHANICAL RECTIFIER' 3 Sheets-Sheet 3 Filed Feb. 12, 1946 uw .um 4m J 7 j J /H JHM w ufl W m 2 F .w n L or Q L Patented Apr. 4, 1950 2,502,932 MECHANICAL Bronnen Eduard Diebold, Zurich. Swltaerland, mig-nor to gesellschaft Brown, den, Switxerland, a io Boverl d: Cie., Ba-

int-stock company Application February l2, 1946, Serial No. 647,003 In Switxerland February 20, 1945 l 14 Claims.

This invention relates to rectiiiers of the contact type and more particularly to an improved arrangement for controlling operation of the rectiiler contacts.

It is well known that the frequency transformation or rectifying of alternating current into direct current and vice versa can be accomplished by periodically actuated contacts. For this purpose, it is well known to employ contact rectiilers with a bridge-like contact that is moved in relation to iixed contacts by means of a pushrod. In this connection, the lifted contact is given a jerking shifting motion and the push-rod an oscillating motion.

The movement of the pusher of the contact must be synchronous with the alternating current supplied to the contacts. The moment of contact making and breaking respectively must be exact, and the timing depends on voltage and current. Satisfactory operation of a moving contact rectiiler of this kind requires that the switching times be maintained exactly and that such times be adjusted continuously to predetermined values in accordance with the variable conditions oi' operation.

Many diiferent devices and means have heretofore been disclosed for controlling these switching movements. A number of mechanical systems are already known, for example, that are operated by a synchronous motor and produce the movement of the contacts by cranks, eccentrics, wobble plates, etc. Various electromagnetic devices arc likewise well known in which the switching movements are produced by the forces of magnetic alternating iields.

The required adjustability of the making and breaking times necessarily makes the purely mechanical moving contact rectifier complicated. Electromagnetic drives permit a simple regulation, but, with the ordinary frequencies, it is difficult to maintain the switching times exactly enough due to the fact the switch operates at high speed. in order to impart to the pusher the required rapid oscillation, it has been necessary to load it with springs. In this way, there is always great danger that additional contact movements will occur because of natural mechanical vibrations. The amplitude and phase position of the imparted movement moreover are greatly affected by these resonant vibrations, the regulation of the switching periods being made diilicult thereby.

An object of this invention is to provide an improved arrangement for actuating the moving contact bridge of a contact type rectifier whereby Y better control over the switching time of the rectiiier is obtained. Another object to provide an improved control for adjusting the period during which the rectiiler contacts remain closed and also the time within a cycle of the alternating current, at which closure of these contacts occurs.

More particularly, an object of the invention is to provide an electromagnet drive for periodically opened and closed contacts, especially of moving contact rectiilers with contact bridges moved in relation to ilxed contact parts. in which, according to the invention, each contact bridge is operated directly by the armature of a special magnet system, the parts of which are movable in relation to each other in an air gap of xed length; at least the ilxed part carries two sets of double poles which inclose alternating current windings, and a direct current energizing winding located between the double poles. The reciprocation of the armature in response to the alternating current may be inuenced by displacing the direct field produced in the air gap by the energizing winding to change the timing of the making and breaking moments of the contacts relative to the alternating current supplying the contacts.

The accompanying drawings illustrate preferred constructions oi rectiiiers embodying the invention and the like parts in the several views are identified by like reference numerals. Fig. l

is a schematic view of a single phase contact rectier incorporating the improved contact control; Figs. 2a-2f are diagrams showing relationships between motion of the push rod which actuates the rectifier contacts and motion of these contacts; and Figs. 3-7 are schematic views of modied constructions wherein the rectier is of the poly-phase type, and wherein the energizing windings are omitted for the sake of simplicity.

Referring now to Fig. l, the moving contact or mechanical rectifier system there shown comprises a source of alternating current such as an alternator I which is connected through transformer 2 to a circuit that includes a pair of ilxed contacts 3 and 3', a contact bridge 5 and a direct current load 4. The bridge 5 is adapted to be moved back and forth against the action of a spring 6 by means of a pusher 1 so that the circuit between the secondary of transformer 2 and the load l is opened and closed periodically. If desired, the rectiiier may be provided with means for preventing the contacts 3, 3' from arcing such as by electronic valves or switchingchokes, or by preliminary energizing, or by impedances connected .in parallel to the contacts, etc. Such 3 devices are already well known and have accordingly not been included in the drawing.

An electromagnetic motor of the reciprocating type is employed for actuating the rectier contacts; the motor being of the type described and claimed in my copending application Ser. No. 638,668, now Patent No. 2,471,729, issued May 31, 1949. This motor includes an elongated armature element which also serves as the push-rod 1 for the contact bridge 5, and a stator, both of magnetizable material, the two elements being slightly spaced from each other to provide an air gap, the armature 'I being supported for movement restricted to a rectilinear path in the directions of the double headed arrow. The stator is formed of two generally c-shaped cores 8, 9 linked by a yoke I0. The ends of the left hand core terminate in a set of pole pieces I I, I2 while the ends of the right hand core terminate in another double pole set comprising pole pieces II', I2'.

The two C-shaped cores enclose operating windings I 3, I3 carrying alternating current and control windings I4, I 4' carrying direct current. 'I'he operating windings I3, I3' are connected in series to a source of alternating current such as alternator I5 through a regulating resistance I6. Alternators I and I5 are synchronized as to speed and phase relation or are driven off the same drive shaft. The control windings I4, I4' are connected in series to a source of direct current such as battery I1 through a change-over switch I8 and a resistance I5. An energizing winding is located between the two cores of the stator beneath yokelll. This winding is connected in series with another energizing winding 2l, that is secured on the pusher 1, between the pole pieces 22, 22' of the same. The energizing windings 20 and 2| are supplied with current from the direct current source I1 through a resistance 23.

Windings 20 and 2| are so wound and connected to battery I1 that when energized, unidirectional magnetic fields of like direction are produced and these set up a single magnetic ux circuit that may be traced starting from air gap 24 through the pole pieces I I, I2, the core 8, yoke I0, core 9, double pole pieces II, I2', across air gap 24', through pole piece 22', armature 1 and pole piece 22. With the armature pole pieces positioned symmetrically with respect to the stator pole pieces, as shown in Fig. 1, the magnetic flux is distributed uniformly on the pole pieces II, I2 and II', I2'.

Operating windings I3 and I3' are so wound and connected to alternator I5 that when energized, magnetic elds of opposite directions are produced which set up separate magnetic flux circuits of opposite directions. The fiux circuit set up by winding I3 confines itself to the magnetic core system 8 and may be traced through pole piece II, core 8 through pole piece I2, across the right half of air gap 24 through pole piece 22, and thence across the'left half of air gap 24 to pole piece II. The flux circuit set up by winding I 3' confines itself to the magnetic core system 9; it takes the same course as the flux circuit in the left half but in a reverse direction.

Control windings I4, I4 when energized from the battery I1 set up unidirectional magnetic iields of such direction that when combined with the alternating magnetic elds set up by windings I3, I3', the unidirectional magnetic eld produced by energizing windings 20, 2| is strengthened in one half of the stator pole pieces. for instance the pole pieces II, I I'. and weakened in the other half, for instance pole pieces I2, I2. In this way, the vunidirectional magnetic eld produced by windings 20 and 2l is displaced laterally and specifically proportional to and in the same direction as the current in the control windvings I4, I4'. This unidirectional eld displacement causes an initial displacement of the armature 1 in relation to the stator and thus determines the operating point of normal zero position of the armature 1. The alternating current in the operating windings I3, I 3' produces a cyclic change in direction of the magnetic eld displacement in the air gaps 24, 24', so that armature 1 moves back and forth in time with the same, and the contact points 3, 3 and 5 are opened and each other yWithout additional mechanical means.

The control can be accomplished directly by variation in the magnitudes of voltage, current and phase.

If the amplitude of the alternating current supplying the operating windings I3, I3' is changed, for instance, with the aid of the resistance I6, the amplitude of the movement of the pusher 1 changes and with it the contact duration di, d2, as will be apparent from the diagrams Figs. 2a, 2b in which the curves show displacement on a time basis of the pusher l' and the contact bri`dge 5, respectively.

With the aid .of the resistance I9 and the change-over switch I8, the control current in the windings I4, I4' is changed in magnitude and direction, and theaxis of symmetry :r of the movement of the pusher 1 is displaced, resulting in a change in contact duration dI, d2, as can be seen in Figs. 20,2211; which show the pusher movement' and the movement of the contact bridge 5, respectively.

An arrangement of three rectiers for converting three phase current to direct current is illustrated diagrammatically in Fig. 3. The rectiers in the several phases are represented schematically by the armature 1, the contact bridge 5, and the windings I3, I3 and Id, I3. The circuit includes a phase-shifting transformer 25 between the alternator I5 and the adjustable resistances I6, and this provides a further control of the timing of the closures of the rectier switches. The making and breaking of all contact bridges 5 may be displaced in common by adjustment of the phase angle between the control current from alternator I5 and the voltage of the power source I, thereby changing the direct current voltage in the load circuit without alternating the duration of the contact closures.

The phase angle between the alternating current supplying the operating windings I3, I3' and the voltage on the rectifier contacts, the amplitude of the currents through the operating windings I3. I3', and the magnitude of the direct current feeding the control windings I4, It' can moreover be changed at the same time. If, for instance.. in Fig. 3, the phase shifting transformer 25, the resistances I5. the resistance I9 and the change-over switch I8 are changed in adjustment at the same time, for example, by connecting them together mechanically by a linkage indicated schematically by dotted lines 26, it is possible to set up any desired value of the closing and opening times of the contact bridges 5. In this way, the amplitude of the alternating current in the operating windings I3, I3 and the magnitude of the direct current in the control windings I4, I4' vcan be adjusted simultaneously so thata variable contact duration is obtained without altering the displacement of the contact bridges 5 from the stationary contacts 3, 3', as apparent from Figs. 2e, 2f. The curve of Fig. 2e shows movement of pushers 1 and the curve of Fig. 2f shows the movement of the contact bridges 5. In the same way, the amplitude of the alternating current in the operating windings I3, I3' and the magnitude of the direct current in the control windings I4, I4 may be varied in such manner that the speed of lifting and closing of the contact bridges 5 is unchanged for changes in contact duration.

An arrangement wherein the period in which contact bridges 5 engage fixed contacts 3, 3 depends upon the load is shown in Fig. 4 wherein alternator I is connected to the primary windings of three phase transformer 2, the secondary windings of this transformer being connected to the load 4 through the sets of rectifier contacts 3, 3 and 5. The operating windings I3, I3 of the contact rectifier are supplied with alternating current from the secondary windings of a three phase transformer 21 whose primary windings are fed from the secondary windings of voltage transformers 28. The primary windings of this latter transformer are tapped into the line connections between alternator I and transformer 2. A regulating transformer 29 has its secondary windings connected into transformer 21 and its primary windings connected to the secondary windings of current transformers 30. The primary windings of the latter transformers are connected in series with respective line conductors that constitute the three phase power supply from alternator I to the primaries of transformer 2.

By adjustment of the regulating transformer 29, it is possible to infiuence the current in the operating windings I3, I3', for instance upon an increase in load 4 on the moving contact rectifier, so that the-contact duration increases correspondingly to maintain a substantially constant voltage in the load circuit. If the primary and secondary windings of the three-phase transformer 21 are so coupled that the currents delivered thereto by the voltage and current transformers 28. 30 are shifted in their phase in relation to each other, it becomes possible for the phase angle between the currents in the operating windings I3, I3 and the alternating current on the contacts 3, 3 and 5 to change with a changing load to alter the time of contact closure to compensate for the drop in voltage when the load increases.

The control windings I4, I 4', of the magnet system can be supplied with direct current from a rectifier 3i. As Fig. 4 shows, the currents delivered by the voltage and current transformers 28,

30, are combined in the transformer 32 with the introduction of another regulating transformer 33. The total current is rectified in the rectifying tube 3| and sent to the control windings I4, I4 through the adjustable resistance I9. A more simple way of suppying power to the windings I4, I4 of all the magnet systems for the alternator I would be to connect them to the incoming lines on the direct current side of the contact rectifier.

An entirely constant load voltage or an entirely constant load current is obtained with greatly fluctuating load when, in the feed lines to the operating and control windings I3, I3 and I4, I4', at least one automatic regulating member is introduced that is influenced by voltage and load of the moving contact rectifier. This is accomplished for instance by changing the adjustment of the regulating transformers 23, 33 of Fig. 4 by a regulator of this kind.

In the case of poly-phase moving contact rectifers, the alternating current operating windings I3, I3 of all the magnet systems may be supplied from one common polyphase synchronous generator 34, as shown in Fig. 5. The generator is driven by a synchronous motor 35, the field of which is energized from battery 36 through resistance 31. If, in this connection, the synchronous generator 34 is constructed with two separately fed energizing windings with different magnetic axes, then by turning the energizing field axis of the synchronous generator out of position, the closing and opening times of the contact bridges 5 of all the magnet systems are displaced in common. r1`he same end can be attained by turning the energizing field axis of the synchronous motor 35 driving the generator, out of position.

If, as in Fig. 5, the field circuit of the synchronous generator 34 is connected to the feed lines of the contact current rectifier on the alternating current side by means of voltage and current transformers 38, 39, transformer 40, rectifier 4I and regulating resistances 42 and 43, it becomes possible for the amplitude, and in certain conditions the phase displacement likewise of the current in the operatingwindings I3, I3' to be adjusted automatically in relation to the voltage on the contacts by the looding of the contact current rectifier. A further possibility for producing the same result is the connection of the energizing circuit of the synchronous generator 34 through resistance to the feed lines of the contact current rectifier at the direct current side.

Also in Fig. 5, a direct generator 44 is provided on the same shaft as` the synchronous generator 34 to supply the direct current control windings I 4. I4' of the magnet system.

The contacts 3, 3 and 5 of the rectifier can be protected from damage by re-ignition, as shown in Fig. 6, by feeding the direct current control windings I4, I4' of all the magnet systems through transformers with three windings that are located in the feed lines of the contact rectifier at the alternating current side.

The transformers have windings 45 in series with the contacts 3, 3' of the associated rectifier, premagnetizing windings 45a energized in series -from the battery I1 through the resistance 46, and windings 45h in series with each other and, as a group, shunted across the serially connected control windings I4, I4 of the electromagnetic motors. In the event of a reignition at one rectifier switch, the resulting current pulse developed in a Winding 45h is transmitted to the control windings I4, I4 to effect a closure of all of the rectifier contacts.

Control of the rectifier can be produced like- Wise by connecting the operating windings I3, I3. of all the magnet circuits into the individual anode circuits of a multi-anode auxilia ry rectifier tube 41, as shown in Fig. 7. The rectifier tube 41 is connected into the alternating current system supplied by alternator I through transformer 48 and suppresses one half of the alternating current wave from alternator I. Control of the grid circuits of rectifier tubev 1 is accomplished by means of a control apparatus 49 of known structure and operation, in dependence on the load or the rectiiied voltage.

The several illustrated embodiments of the invention indicate the wide latitude which is possible in the construction of a mechanical rectifier which is controlled by adjustment of electrical values, and it is to be understood that other arrangements fall within the scope of the invention as defined in the following claims.

I claim:

l. In a mechanical rectiiier, a stationary contact, a movable contact, means biasing said movable contact into engagement with said stationary contact, and a flux polarized electromagnetic motor for actuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and lift said movable contact out of engagement with said stationary contact, winding means carried by one of said elements for energization with alternating current to produce a periodically reversing ilux that effects a periodic axial displacement in the path taken by the polarizing ux at the air gap between said elements and hence a like displacement of said armature element in opposite directions from a central position, and means for adjusting the amplitude of said alternating current to thereby effect a corresponding adjustment in the magnitude of the displacement of said armature ele- 2. A rectifier as defined in claim 1 and which further includes a phase shifting device in the alternating current supply for said winding means tfor altering the phase relationship between the current therein and the voltage rectified through said contacts.

3. A rectifier as dened in claim 2 and which further includes means for operating said phase shifting device and adjusting means for said alternating current simultaneously.

4. A rectiiier as dened in claim 1 wherein the adjusting means for said alternating current are operated automatically in accordance with the rectifier load.

5. A rectier as dened in claim 1 wherein said winding means is energized from the output of a transformer, the input to which is constituted by the electrically combined outputs of voltage and current transformers connected in the power supply line to said rectifier contacts.

6. A rectifier as defined in claim 1 wherein said winding means is energized from an alternator, the field energization of which is varied automatically in accordance with the rectier load.

7. A rectier as deiinedin claim 6 wherein the field energization of said alternator is derived through an auxiliary rectier the input voltage to which varies automatically with the load on the main rectifier.

8. A rectiiier as dened in claim 1 and which further includes means suppressing one half of the wave of alternating current energizing said Winding means.

9. In a mechanical rectifier, a stationary contact, a. movable contact, means biasing said movable contact into engagement with said stationary contact, and a flux polarized electromagnetic motor for actuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and` lift said movable contact out of engagement with said stationary contact, winding means carried by one of said elements for energization with alternating current to produce a periodically reversing flux that eects a periodic axial displacement in the path taken by the polarizing iiux at the air gap between said elements and hence a like displacement of said armature element in opposite directions from a central position, and auxiliary winding means carried by one of said elements for energization with direct current for eiecting an initial axial displacement of the polarizing iiux path and armature from said centrol position.

10. A rectifier as defined in claim 9 and which further includes means for automatically varying the magnitude of the direct current in said auxiliary winding means in accordance with variations in the load on said rectifier contacts.

11. In a mechanical rectifier, a stationary contact, a movable contact, means biasing said movable contact into engagement with said stationary contact, and a flux polarized electromagnetic 4motor forvactuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and lift said movable contact out of engagement with said stationary contact, Winding means carried by one of said elements for energization with alternating current to produce a periodically reversing iiux that eiiects a periodic axial displacement in the path taken by the polarizing iiux at the air gap .between said elements and hence a like displacement of said armature element in opposite directions from a central position, and auX- iliary winding means carried by one of said elements for energization with direct current of selectable direction and amplitude to eiect an initial axial displacement of the polarizing `flux path and armature in one direction or the other from said central position.

12. In a mechanical rectiiier, a stationary contact, a movable contact, means biasing said movable contact into engagement with said stationary contact, flux polarized electromagnetic motor for actuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and lift said movable contact out of engagement with said sta- .tionary contact, winding means carried by one of said elements and energized with alternating current for producing a periodically reversing flux that eiiects a periodic axial displacement in the path taken by the polarizing flux at the air gap between said elements and hence a like displacement of said armature element in opposite directions from a central position, and auxiliary winding means carried by one of said elements and energized with direct current for effecting an axial shift in the polarizing ux path at the air gap to thereby vary the central position of said armature, a current transformer havingprimary, magnetizing and secondary windings,

means connecting said primary winding in the input side to said rectifier contacts, means energizing said magnetizing winding with direct current, and means connecting said secondary winding in circuit with said auxiliary winding means.

13. In a mechanical rectifier, a stationary contact, a movable contact, means biasing said movable contact into engagement with said stationary contact, and a ux polarized electromagnetic motor for actuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and lift said movable contact out of engagement with said stationary contact, winding means carried by one of said elements and energized with alternating current automatically varied in accordance with the rectifier load for producing a periodically reversing flux that effects a periodic axial displacement in the path taken by the polarizing fiux at the air gap between said elements and hence a like displacement of said armature element in opposite directions from a central position, and auxiliary winding means carried by one of said elements and energized with direct current varied automatically in accordance .with the rectifier load for axially shifting the path of the polarizing flux at the air gap to thereby vary the central position of said armature.

14. In a mechanical rectifier, a stationary contact, a movable contact, means biasing said movable contact into engagement with said stationary contact, and a fiux polarized electromagnetic motor for actuating said movable contact, said motor including an armature element arranged for reciprocating motion relative to the stator element to periodically engage and lift said movable contact out of engagement with said stationary contact, winding means carried by one l0- of said elements, and means for energizing' said winding means with a periodic time varied current to produce a correspondingly varied flux effecting periodic axial displacement in the path EDUARD DIEBOLD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,131,896 Ballman Mar. 16, 1915 1,676,979 Cheeseman VJuly 10, 1928 1,823,326l Legg Sept. 15, 1931 1,878,919 Van Dam et al. Sept. 20, 1932 FOREIGN PATENTS Number Country l Date 875,968 France July 13, 1942 

